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Tuesday, October 30, 2012

Their evolution is replete with adaptations to survival that are kind of mind blowing but as with all insanely unusual things, the ideas can be a little unsettling and frankly... a little SPOOOOKKKYY................

1. They don't seem to know when to die...
Most biologists have noticed that echinoderms don't quite die immediately when threatened with the kind of life-threatening injuries that many would consider life-threatening. Or else..its the WRONG part of the animal that seems to go on living... [Yes, some do regenerate (and that will be a subject for a future post!) but not all.] Some examples:

The Story of Stumpy

Here is a true story (although I don't remember who told me this story originally)

Years ago, following a lab accident or perhaps a crab run amok, the disk and 4 arms from a sand starfish (Luidia clathrata) was separated from the mid to end part of its 5th arm.

Contrary to popular myth, not all starfish can regrow a complete body from just the arm. This one certainly could not.

This separated arm tip (which was named "Stumpy") was kept in the water table and continued to move around for weeks to months...(I honestly don't remember how long but it was a long time).

Stumpy was even "fed" clams, which it apparently moved via tube feet to where it thought the mouth was. These clams would move up the tube foot groove and then just...fall out when it reached the disk location. No disk! (and thus no mouth)

It was never clear to me if Stumpy just sort of died on its own or if it creeped everyone out so much that they eventually just preserved it in the lab somewhere.

This isn't necessarily unusual "behavior." One can often observe the arm of a brittle star sometimes continue to move long after it is separated....

Presumably a combination of the unusual radial nervous system and the separated body part's ability to sustain itself using sea water (and nutrients) were responsible for this tenacious behavior?

But why believe an echinoderm zombie story when you can simply watch it...

Here is a "Zombie" Sea Urchin..The animal is broken open with insides removed and yet....IT LIVES

2. Uh... Do Echinoderms ever die of natural causes??
As a person who has worked in and out of museums and aquariums, one of the things you notice is how some species kept in captivity become bigger and bigger..

Some species such as Pycnopodia helianthoides (from the North Pacific coast)

Photo by Allison Gong

And the enormous Pisaster brevispinus, approach three FEET in diameter (that's about a meter for those outside the US).

Photo by Mr. J. Volz

When kept in captivity sea stars have no predators, are fed every day, and generally don't undergo much, if any, kind of stressors. Its never been clear if any of them perish of "natural causes."

Now, to be clear-they do die. Diseases, aquarium mishaps, introduced predators and so on.

But under optimal conditions?? I have had people watching these cold water species live on for over 10 years (but I'll be honest I would need to verify) and more than once I've been asked "Do they EVER just die of natural causes??"

And honestly, I don't know if they do. Some accounts from the 1960s reported that they became "reproductively senile" but this account was speculative.

So next time you go into say hello to a large sunflower star at your local aquarium-pay it some respect. It might be much older than you are...

3. Some of them GLOW in the Dark!
There is a whole POST worth of stuff on bioluminesence in echinoderms! And at some point in the near future I will write up more about it..but for now accept that a LOT of echinoderms glow!

And here is a neat video that shows the bioluminescent granular covering off a deep-sea swimming sea cucumber..

4. They way some of them go after prey, If they were bigger, WE would be afraid of them!
Most people seem to have a fairly benign impression of echinoderms. Harmless shapes that sit on the bottom of the sea floor that make up part of a dreamy seascape...

Here at the Echinoblog I've done everything I can to change this image!

Many starfish and brittle stars can capture MOVING prey and do so in a variety of surprising ways. Imagine ANY of these things as dog or even COW sized and humans would be more respectful of the humble echinoderm...

5. Dried Echinoderms are MUMMIES, NOT shells
This is probably one of the more macabre things that I've made note of before. Undoubtedly we have all seen starfish decorations for the holidays and weddings??

A sad Pisaster ochraceus

sad Linckia laevigata

So, let's remember/invoke some basic biology about ALL echinoderms here. Remember that ALL echinoderms have skin covering OVER their endoskeleton.

When sea star (or ANY echinoderm) is prepared dried this way?

This isn't the same as some shell. There is/was skin on them. THESE ARE MUMMIES.

What you are doing above? Is like putting funny clothes on a skeleton or a mummy like this... (which I suppose is fine if you realize what you're doing..)

Monday, October 22, 2012

This is one of those RARELY seen animals that I love sharing with people because they are SO strange.

First lesson: Ctenophores are a group similar in appearance to jellyfish. But in a separate phylum-The Ctenophora. Here's the Wikipedia for handy-dandy quick reference. They are identified by "ctene rows" that are what they use to propel themselves. Underlight these ctene rows shimmer giving them an iridescent appearance which looks like this:

But there's one subgrouping of comb jellies that, for some odd reason, have taken to living on the sea bottom-sometimes on other animals, such as sea stars but also on sea urchins and corals.

Its thought that these are commensal relationships. In other words, the ctenophores live at no apparent "cost" to the host. But relationships are poorly understood-so who knows?

At the very least having THAT many ctenophores crawling around on your surface might clog up your papulae for respiration and so forth.

The animals are those strange moving white blobs on the surface. The ones living on the sea stars are in the genus Coeloplana. I'm not sure if the ones further down that are not living on sea stars are the same genus.. but I'm guessing probably not.

Those threads? Are the feeding tentacles that you would normally see here in the "sea gooseberry" Pleurobrachia

But here is Some neat NEW Benthic Ctenophores on Echinaster callosus! Shot in Lembeh

here is the FIRST video of benthic ctenophores as shot by Blenny Watcher. Host is Echinaster luzonicus

Here are some from Bocas Del Toro, Panama without the sea star host. Shot by Rosana Rocha

So, today is National FOSSIL DAY! WOO!! and y'know, I figure WHAT do people WANT to see on National Fossil Day???

OBVIOUSLY the answer is PARASITES!! (and related stuff like commensals!) Everyone LOVES parasites! Especially echinoderm parasites! Its especially exotic when you can see them as fossils!

To be fair, some of the relationships below are probably better described as "commensal" which means that one derives gain from the host without the host losing resources..

What's often most exciting about these kinds of fossils is that we actually have DIRECT EVIDENCE of animal interaction! Which for the fossil record is often difficult.

We can see that fish had big bone-crushing teeth and we can even see broken snails nearby on a fossil deposit, but after 300 million years, you have to be careful about conclusions. This is often what makes good reliable evidence of paleoecology so valuable..

Here are 5 interesting cases of parasitism/associations/commensals on echinoderms from the fossil record! There are undoubtedly more...

1. Paleozoic Platyceratid Snails on Stalked Crinoids!
This one is probably one of the best known among fossils. Basically there is one Paleozoic group of snails belonging to the family Platyceratidae. They often look like this:

Image by Ivanvlee8 on Flickr

Multiple genera have been observed in a specific position right on top of the calyx or "cup" in stalked crinoids.

Here's what the animal typically looks like to give you a general bearing.

What the snails seem most interested in is the anal cone found on the TOP of the cup (this is the area where the mouth is found and is surrounded by the feeding arms). They are often found clamped down over the anus.

Most interpretations suggest that platyceratid snails are COPROPHAGES. That is a special kind of feeding which specializes on consuming POOP!

There are literally dozens of papers on the paleoecology and biology of these animals..and so I will leave this interaction to be written up in a later blog... But platyceratids are found on MANY different crinoids AND other stalked echinoderms from the Paleozoic, such as blastoids (see this account by Tom Baumiller)!

and also in this specimen of the same species showing more of these discrete holes on the test...

These holes were compared against the kinds of holes made by modern day gastropods in the family Eulimidae which are often seen as parasites on starfish such as the blue Linckia laevigata shown here... (images by Sven DeVos on Flickr)

Snails like this basically pop their proboscis into the body wall and take advantage of the host as prey. Its thought that they occur on a relatively low number of the total population.

Neumann and Wisshak observe this on 19 different locations (and thus 19 individual parasitic forams) on the test of this fossil sea urchin! Note that the big curvy worm tube isn't part of the foram traces...

Here Wisshak and Neumann document borings in the sea urchin's skeleton via the work of an industrious polychaete worm-a polydorid! Such worms bore though hard substrates and are asociated with tunnels such as this:

Image by elegaer on Flickr

But how can you be SURE that these worms didn't just find the dead animal's skeleton and bore through that?? Why make the jump to "These holes were made in the animal when it was alive"???

This cartoon basically shows that following the worm's "boring" through the skeleton and the deformation of the skeleton by the worm..the surface spines and other structures- pedicellarie, etc. ALL REGREW over the area that had been "bored" through!!

It seemed like THIS year, it might be fun to actually show what some of the characters from Japanese pop culture (movies, TV and toys! actually LOOK like! (esp. with Halloween just a few weeks away)

GEZORA the giant cuttlefish from Yog-the Monster from Space!
Gezora stands 30 meters tall (98 feet) and apparently weighs 20,000 tons! Basically- a cuttlefish infected by extraterrestrial microbes! It kicks ASS! It first appeared in the 1970 classic "Space Amoeba" produced by Toho-the fine people who bring you the Godzilla movies!

Here's a neat slide show of various posters and screen shots from the movie...

from the people who broughtyou Godzilla! Gezora shows up at 0:50

THE CALAMARI WRESTLER!
This movie came out in 2004. Its about uh...well, a wrestler who becomes a giant squid! One great part of this flick? In the end he goes toe to toe with ANOTHER giant invertebrate! (no spoilers though!)

Japanese Cephalopod TV Monsters!

There's a long history of super heroes on TV in Japan-you've probably heard of characters such as Ultraman or the Power Rangers but one of the more popular, but less well-known in the US (unless you live in Hawaii) are franchises such as Masked (or Kamen) Rider.

Almost all of these shows were serialized and went from week to week with a monster every episode.

What happens when you have to create a monster for your hero to fight every week?? You come up with a creative theme that's what! Here are just a few of the ones I'm fond of!

A neat monster whose particular distinction was that the ammonite (serving as the monster's head) was kicked OFF his body early in the episode, leaving the rest of him wandering around and chasing after it!

The disembodied ammonite, in the meantime befriended a small child and learned the meaning of kindness. I don't make this stuff up!

From Ultraman 80 the gigantic octopus monster DARRON! Ya' just gotta love how they work the tentacles over the legs in all of these costumes..

The big bad GATANAZOA from Ultraman Tiga! Kind of a hybrid between a crab and an ammonite..

There are undoubtedly more! And one of these days..maybe I'll follow up...

CEPHALOPOD TOYS!

What I love about the Japanese culture is just how serious they take their collectibles and toys. Great care is given to items in a way that is seen nowhere else in the world..

For example, here is an ammonite "candy toy"-an item that usually accompanies a piece of chocolate or some other item (kind of the way a baseball card used to accompany chewing gum).

There is a series of these items that one collects and people sometimes hundreds of dollars to chase down a complete set of these...(the other items are mostly dinosaurs and other giant marine reptiles)

This represents an actual species of coiled shell ammonite-but not sure off the top of my head, which one it is..

And where would we be without a transforming robot?? This one is a bit of cheat since I think this might be something easily available in the US.. But its from Beast Wars: Transformers-and is called "Neo Dead End"

It goes from this...

To this...

Its great to see how cephalopods- and not just living ones-but fossils have worked their way into international pop culture! (now let's just hope that people who see these things figure out what inspired them!)

Wednesday, October 3, 2012

The Gilbert Harris Award is presented annually by the Paleontological Research Institution in recognition of career excellence in systematic paleontology. It is named after the founder of PRI, Gilbert Dennison Harris (1864-1952), whose commitment to systematic paleontology was legendary. The annual recipient is a scientist who, through outstanding research and commitment to the centrality of systematics in paleontology, has made a significant contribution to the science. PRI is pleased to announce that this year’s recipient is Dr. Daniel B. Blake, Professor Emeritus of Paleobiology in the Department of Geology at the University of Illinois Urbana-Champaign.

Dr. Blake’s contributions to the field of systematic paleontology, particularly of stelleroid echinoderms and bryozoans, have been significant and far-reaching. He was part of a large team that revised the bryozoanTreatise of Invertebrate Paleontology in the early 1980s, and his work on Rhabdomesina is still the benchmark for systematics of this group. According to his nominating colleagues, he is essentially the only paleontologist who specializes in the fossil record of the Asteroidea, and it is for his systematic and phylogenetic work with this group that he is best known. His approach, combining a critical understanding of functional morphology with deep geologic knowledge of their history, has allowed him to develop a cladistic approach to their phylogeny that serves as a model for all. He might also be the only person in the world to have examined representative specimens of every known genus of modern and fossil seastar. He currently serves as lead author on the upcoming revision of the Treatise Asterozoa volume.Dr. Blake’s publication record is extensive and influential. In addition, he was for many years the influential editor of the Journal of Paleontology, one of the premier journals of paleosystematics. Working at a time when manuscript exchange was done via the U. S. Mail, he was essentially a one-man show. His standards were high and unyielding, and many paleontologists remember the rigorous comments they received on their manuscripts. His dedication to science and the journal contributed to the high quality of that publication today.

Dr. Blake is also lauded as an excellent field geologist, a respected mentor of students in systematic paleontology, and a friend and supporter of amateur collectors. It is with pleasure and honor that the Paleontological Research Institution presents its 2012 Gilbert Harris Award to Dr. Daniel B. Blake.

Dan Blake was my PhD advisor and I (as well as his many students!) are excited to see that his expertise is being appreciated and honored!

Tuesday, October 2, 2012

I betcha you guys didn't know that starfish left FOOTPRINTS did ya?? I don't just mean impressions on the sand..I mean, put a starfish on a smooth surface, like glass or rock and it leaves you one of these...

WHAT?? How does THAT work?
Hasn't the model always been that starfish tube feet work like suction cups (such as here) ???? Why would they leave footprints on a smooth surface if they work like suction cups??

So, it turns out that the whole tube foot adhesion process is a LOT more complicated than the whole "its a suction cup" explanation that used to be offered in text books.

It turns out that the whole chemistry and physical processes of tube foot adhesion is actually quite complex and has very useful applications in adhesives, glues and so forth.

There is an important lesson to be learned here. This field of study started largely as an academic pursuit, to learn about the mechanisms used by these animals to survive in their habitat but may soon lead to something with many practical applications..

See this article awhile back about how Gecko adhesion has led to new types of adhesives! Adhesives that work under water would presumably have a multitude of uses..

1.Contact!The process begins with the contact of the tube foot with the ground/substratum.

There is a special layer called the "fuzzy coat" (shown below in red) which is present on the surface of the disk epidermis making contact with the bottom.

Echinoblog Art Dept.- Note that "Smuck" is not known to be a true starfish tube foot noise!

2. "Film" Upon contact two different kinds of special "adhesive cells" release substances onto the substrate (aka the ground) which form an even film (shown in green below).

Echinoblog Art Dept. Did you know that ! can be used to make everything more exciting?!!

3. "Mesh" At this point one of the adhesive cells releases a substance that starts to form a thick "meshwork structure" (shown below in yellow) in the fuzzy coat. The mesh expands and "bulks up" creating more structure within the fuzzy coat.

Echinoblog Art Dept. Coloring is fun!

Here is an SEM of what this looks like...

fig. 1B from Hennebert et al. 2008

4. Detachment. When the tube foot releases, a THIRD substance-a "de-attaching" substance is released from the disk epidermis. This is something that permits the tube feet to detach easily and at the animal's will.

This leaves the "fluffy layer" and the "bulked" material behind...

Here is an SEM of what this looks like after the tube feet have been pulled away

Figure 2C from Hennebert et al.

5. Footprint And the wet parts of the "fluffy layer" dry out leaving the "bulked" material aka the starfish (or whatever) footprint..

Here is what that part which is left behind looks like in 3D via Transmission and Atomic Force Microscopy

Fig. 3 from Hennebert et al.

And here is an image of the tube foot "foot print" as seen directly off a piece of glass..

And so...
What about that classic paradigm about suckers on sea stars and other echinoderm tube feet basically being suction cups???

Well, nothing definitive has been published as yet..but Flammang's lab has published on these adhesive processes in tube feet for over 10 years. A title from an oral presentation at one of the last European echinoderm conferences by Elise Hennebert, Romana Santos and Patrick Flammang here, entitled "Echinoderms don't suck" does seem to imply the days of that mechanism are numbered.

Bear in mind that this doesn't even necessarily end with this one tube foot type. There are at least two other forms of tube feet and exploring the various mechanisms at play could be fruitful indeed...

In addition to the lab run by Patrick Flammang at the University of Mons, this lab in the UK (shown in this video) has also undertaken research into this area to understand the nature of tube foot adhesives...

About Me

I pursue starfish related adventure around the world with a critical eye and an appreciation for weirdness.
Support has been courtesy of the National Science Foundation but the views and opinions presented herein are mine and do not reflect the opinions of them or any affiliated institutions.
Need to hire an invertebrate zoologist/marine biologist? Please contact me!